Piston skirt expander



1 1936- G. J. MOELLER PI STON SKIRT EXPANDER Filed Oct. 31, 1955 1 9 mu m MM w w 7 9 J s w .a 2 B e m a a G. J. MOELLER 2,027,872 PISTON SKIRT EXPANDER Filed Oct. 51, 1955 5 Sheets-Sheet; 2

Jan. 14, 1936.

IIIIH ||||1|| I Illlll T [lllll Hlllll lllllll' Ulllllll IIII ll Jan. 14, 1936. G. J. MOELLER PISTON SKIRT EXFANDER- Filed Oct. 51, 1955 3 Sheets-Sheet 5 Ill/All!!! A HII I l I I Patented Jan. 14, 1936 OF F ICE PISTON SKIRT G om J- gl e ler st. Long l lo minor to Ramsey coesso cs Man acuring Corporatlon,8t. Iiouls, Rio-,acorporationofMiuom-i Application October 31, 1985, Serial No. 47,604 20 Claims; (Cl. 309-12) My invention-has relation to improvements in piston skirt expanders and consists in the novel features of construction more fully set forth in the specification and pointed out in the claims.

It is well known in the automotive art that aluminum alloy pistons after a continued of an appreciable period of time have a ten ency to collapse in the skirt. This is primarily due to the provision of lateral and longitudinal slots expansion under heat between the alloy of the piston andthe cast iron of the cylinder. It has now became common practice to place a device, known as an expander, within the skirt of alloy pistons for the purpose of preventing or overcoming the collapsed condition, and also for the purpose of maintaining or restoring resilience to the skirt. These expanders may either be placed within a new piston or within a piston that has already become collapsed or deformed in use.

There are various types of expanders now in use, among which are devices for spreading the skirt at the slot therein, annular devices or rings disposed within the skirt and also U-shaped springs adapted to exert their tension at diametrically opposite points within the skirt.

It is to this last type of expander that the present invention relates and has for its principal object the providing of a U-shaped spring that spans the skirt in a direction at right angles to the axis of the piston pin bosses (of the general shape as that shown in the patent to Hall No. 1,625,120), together with securing means adapted for engagement with the ends of the spring and anchored by suitable means on the inside of the piston skirt.

It is a further object of the present invention to provide a U-shaped expander for piston skirtsof the expander, which shoes may be provided with suitable gripping means for engaging the skirt, or may be adapted to cooperate with structural formations of the piston. Among the advantages of the detachable shoes are that they may be used with U-shaped springs of various weights and degrees of tension. A further advantage of the shoes with gripping means is that they may be disposed vertically at any location within the piston skirt in order to effect the expansion thereof as desired.

A further object of the invention is to provide a U-shaped expander that is adjustable as to size so that the same expander may be adapted 55 to pistons of diirerent sizes.

in the skirt essential to counteract the unequal Further and other advantages will be better apparent from a detailed description of the invention in connection with the accompanying drawings, in which:

Figure 1 is a middle, longitudinal sectional 6 view taken through a piston on a. plane at right angles to the axis of the piston pin bosses showing my improved expander disposed within the skirt of said piston; Fig. 2 is a bottom plan view of said piston showing the expander 10 therein; Fig. 3 is a vertical, longitudinal sectional view taken on a plane indicated by the line 3-3 in Fig. 1; Fig. 4 is an enlarged longitudinal sectional, view through the expander shoe and the end of the expander connected there- 16 with, the portion of the piston wall engaged by said shoe also being indicated; Fig. 5 is a face view of the expander shoe detached from the spring and looking toward the outer face of the shoe; Fig. 6 is an enlarged longitudinal sectional 20 view taken through the shoe on the line 6-6 of Fig. 5, showing the shoe in its free or relaxed position; Fig. 7 is a view similar to Fig. 1 except that a modified form of expander is shown in which the upper ends of the shoes are shown in 2d engagement with the edges of the transverse slots formed in the piston above the skirt; Fig.

8 is a side elevation .of the upper part of the piston shown in Fig. '7 showing the upper part of the expander shoes wedged in the transverse 8 piston slot; Fig. 9 shows a longitudinal section of the lower part or the skirt portion of a piston showing a modified form of expander in which the shoes for anchoring the expander are formed integrally with the spring thereof; Fig. 10' is a 35 longitudinal sectional view showing the skirt portion of a piston equipped with an annular or ring-type expander held in place by shoes similar to those shown in Figs. 1 to 6, inclusive; Fig. 11 is a transverse sectional view taken 40 through the piston skirt shown in Fig. 10 on a. plane indicated by the line H-ll thereof; Fig. 12 shows a longitudinal section of a piston skirt equipped with an expander in which the lower edges of the shoes are provided with flanges for 4 disposition within recesses cut into the inner surface of the piston skirt; Fig. 13 is a view similar to Fig. 12 showing a piston skirt having a terminal flange at its lower end, and an expander having shoes terminating at their lower 50 ends in channels for engagement with said terminal flange; Fig. 14 is a viewsimilar to Figs. 12 and 13 showing a piston having spaced annular flanges at the lower end thereof and an expander having shoes adapted to be sprung into place between said flanges: Fi s. 15 and 18 show a side elevation and bottom plan respectively of a modifled form of expander which is adjustable as to size for different sizes of pistons; and Fig. 17 is a middle, longitudinal sectional view taken on the line Il-I'I of Fig. 15.

Referring to the drawings, and for the present Figures 1 to 6, inclusive, P represents a conventional form of alloy piston having transverse slots 1!, t between the piston head and skirt, and a longitudinal slot 3 extending from one of said transverse slots to the lower end of the piston. The piston is provided with the usual pin bosses b, b. A skirt expander comprising a U-shaped spring I and securing shoes 2, 2 is disposed within the piston skirt and extends diametrically from side to side thereof in a direction at right angles to the axis of the piston pin bosses b, b. The purpose of the shoes 2 is to securely anchor the spring I within the piston skirt and accordingly is provided with grlppingmeans in the form of a serrated upper edge 3 and a serrated lower edge 4. Obviously, instead of serrating the edges 3 and 4 along their entire length, a few teeth may be formed in said edge. Intermediate the edges 3 and 4 of each shoe 2 is formed a transversely disposed recess 5 to serve as the receiving hinge element for a bead i formed on the outwardly bent extremity I of each arm 8 of the spring I. The metal of each shoe 2 is extruded adjacent to the recess 5 at the points 9, 9' for the purpose of slightly restricting the opening 5' to the recess Ii. The width of the restricted opening 5' is slightly less than the diameter of the bead 3 so that the bead may be manually forced into the recess 5 so that the shoes 2 and spring I may be held together in assembled relation. A toe III is protruded outwardly from the body of the shoe 2 between the extruded portion 3 and the upper end thereof.

When the expander is not under tension within a piston skirt the portions of the shoes 2 above and below the respective portions 9 and 9' are disposed at a somewhat greater angle to each other than when the expander is under tension within the skirt. This will be apparent by a comparison of Figures 4 and 6. The flattening of the shoe 2 under the pressure imposed on it by the spring I causes the toe ID to dig into the metal of the cylinder skirt wall to more flrmly anchor the shoe thereto. This flattening of the shoe also causes the extruded portions 9 and 9' to approach each other and further constrict the opening I. Since the shoe 2 must engage with a cylindrical surface it is formed with a slightly transverse curvature (Fig. 2) to engage this surface. The hinged element 5, for the sake of simplicity of manufacture, is also slightly curved. Therefore, in order to permit of a slight hinge movement between the shoes 2 and the spring I the bead 3 flts into the hinge element 5 with clearance. The advantage of the hinge action between the spring I and shoes 2 is that it permits of limited movement of the shoes so that they may adapt themselves to any irregularities that may be encountered within the piston skirt.

After the expander has been in use within a piston for a considerable period of time the pressure exerted against the shoes, 2, 2 by the spring arms 3 will have forced the toe I into the wall of the piston skirt so that the shoes become flattened against said wall. Of course. the extent of this action is not uniform and will depend largely upon the hardness of the metal of which the piston is composed.

One of the principal advantages of the skirt expander shown in Figures 1 to 6, inclusive, is that it may be applied to any type of piston in that it does not depend upon formations within the piston to hold it in place. Another great advantage is that in the manufacture of the expander one size of shoes may be used with different sizes and weights of springs so that in the production of the expander only the springs need be varied in making up sizes for different sizes of pistons.

In the modification shown in Figures 7 and 8, the spring I is the same as in the main form but the shoes II, II are modified in that they are extended upwardly and have their upper ends terminate in corrugated, laterally extending flanges I2, I2 for insertion in the transverse slots t, t of the piston. The action of the expander in use is the same as in the main form.

In Figure 9 the expander I3 is modified in that the shoes I4, I4 are integrally formed with the spring arms I5, I as shown.

In Figures 10 and 11, I show a ring-type of expander I6 having hinged connection with oppositely disposed shoes l1, l1 similar to the shoes 2 of my main form. The expander I3 is provided with a gap I3 and the ends of the expander I9, I9 are turned inwardly to facilitate the insertion of the expander within the piston skirt. However, the expander may be in the form of a continuous ring, as indicated by the dotted lines 20, if desired, although this type of expander may be somewhat more diflicult to insert within the piston skirt.

In Figure 12 the expander shoes 2|, 2| have outwardly extended flanges 22, 22 on their lower ends and are disposed within kerfs 23, 23 cut into the inner surface of the piston skirt.

In Figure 13 the expander shoes 24, 24 have channel formations 25, 25 at their lower extremities for engagement with a terminal flange 26 on the piston.

In Figure 14 the expander is adapted to a piston P which is provided with a .terminal flange 21 and an annular rib 28 spaced a short distance inwardly therefrom. The U-shaped spring I is similar to that of the main form, but the shoes 23, 29 are shorter and are adapted to be sprung into the space between the flange 21 and rib 28.

In the modification shown in Figs. 15 to 17, inclusive, I show the spring element 30 of the expander formed in overlapping sections 3|, 32. The section 3| has a tongue 33 at one end and an outwardly bent flange 34 at the opposite end, while the section 32 has a transverse strap 35 pressed downwardly from one end and has a series of grooves 36 formed transversely near its opposite end. An inspection of Figure 1'7 will show that the tongue 33 of the section 3| is confined between the body of the section 32 and the strap 35, while the flange 34 is disposed in one of the grooves 36. By moving the sections longitudinally relative to each other the flange 34 can be made to enter any of the grooves 33 for adjusting the length of the spring element 30. The section 3| has a bead 31 at its lower end, and the section 32 has a bead 33 at its lowerend to form hinge elements for cooperation with the expander shoes, which are not sh wn,but may be of any of the forms shown in the other flgures. Instead of the flange 34 and grooves 33, the expander sections 3| and I2 may be provided with protuberances and indentations respectively. Such formations are an obvious equivalent of the construction shown.

Having described. my invention, I claim:

1. A piston skirt expander comprising a U- shaped spring element, and piston engaging shoes hinged to the ends of the spring element, said shoes being provided with skirt gripping means.

2. A piston skirt expander comprising a U- shaped spring element, piston engaging shoes at the ends of thespring element, said shoes bein provided with skirt gripping means, and means for adjusting the length of the spring element.

3. A piston skirt expander comprising a U- shaped spring element, piston engaging shoes at the ends of the spring element, and cooperating formations on the spring element and the shoes for connecting the shoes to the spring element.

4. A piston skirt expander comprising a spring element, piston engaging shoes associated with said spring element, cooperating formations on the spring element and the shoes for connecting the shoes to the spring element.

5. A piston skirt expander comprising a U- shaped spring element, piston engaging shoes at the ends of the spring element, and means for hingedly connecting the shoes to the spring element.

6. A piston skirt expander comprising a spring element, piston engaging shoes associated with the spring element, cooperative formations on the spring element and shoes for connecting the spring element to the shoes, said formations comprising an expansibie loop and a head of such proportions as to permit forcing the bead into the loop.

7. A piston skirt expander comprising a spring element, piston engaging shoes connected to the spring element, the connection between the spring element and the shoes comprising a snap-joint.

8. A piston skirt expander comprising a U- shaped spring element and piston engaging shoes hinged to said spring element.

9. Apiston skirt expander comprising a spring. element and piston engaging shoes hinged to said element, said shoes being provided with nglatns for retaining said expander in a pisto s 10. A piston skirt expander comprising a spring element and piston engaging shoes pivotally connected to said spring element.

11. A piston skirt expander comprising a U- shaped spring element, piston engaging shoes at the ends of the spring element and means at one of the ends for hingedly securing the shoes to the spring element.

12. A piston skirt expander comprising a U- shaped spring element and means at one end thereof for hingedly securing the spring element with respect to a piston skirt.

13. As an article of manufacture, a shoe adapted for use in connection with a piston expander, said shoe being provided with means for securing the same to a piston, and'also being provided with means for pivotally securing the same to an expander.

14. As a new article of manufacture, a piston expander provided with means at both ends for hinging the same with respect to the wall of a piston.

15. As a new article of manufacture, a shoe for use in combination with a piston skirt expander element, said shoe comprising a'strip of metal having formations which may penetrate into the metal of a piston skirt, and also having means for pivotaily mounting the same upon a piston skirt expander element.

16. As a new article of manufacture, a piston skirt expander element comprising a strip of spring material having a bead at opposite ends thereof.

17. As a new article of manufacture, a piston skirt expander element comprising a strip of spring material having means constituting one element of a pivotal connection.

18. As a new article of manufacture, a shoe for use in combination with a piston skirt expander element, said shoe comprising a strip of spring metal having spaced, transverse extrusions, the adjacent surfaces of said extrusions having portions curved toward each other and forming a bead-receiving recess.

19. An expander for use in a piston, said expander consisting of a resilient strip of spring material having a head on at least one end thereof, and a piston skirt engaging shoe having a recess adapted to receive said bead and being mounted upon the beaded end of said strip.

20. In combination with a piston having a flanged skirt, an expander therefor comprising a U-shaped spring element, and piston engaging shoes at the ends of the spring element, said shoes being provided with means engag ng said flange, said means comprising a channel formed in said shoe.

GEORGE J. MOELLER. 

